1. Field of the Invention
The present invention generally relates to microphone technology. More specifically, this invention is directed to a shroud, and related method, for mounting over a helmet-mounted microphone, such that undesirable environmental noise is attenuated, yet desired input signals are not so attenuated.
2. Description of the Related Art
Outdoor microphones are widely used in various applications by various people including television reporters, public addressers, movie makers, and motorcycle riders. These microphones are generally exposed to extremely harsh environmental conditions including wind noise, traffic noise, and vibrational noise. Such noise adversely affects performance of microphones in terms of sound quality transmission. Therefore, it is important to protect the integrity of the microphone output signal by better isolating desired voice input signals from undesired environmental noise.
The prior art has suggested various methods of mitigating the effects of environmental noise on microphone output quality. A classic example is use of a noise suppressing filter mounted over the microphone as taught by Knutson et al., U.S. Pat. No. 3,154,171. Knutson et al. disclose a conventional microphone having a porous urethane wind screen enclosing the microphone on all sides. The wind screen acts to diffuse wind turbulences before they reach the microphone. Such an article is more commonly known today as a windsock, is typically composed of open-cell foam, and is widely used on microphones of many different varieties. One disadvantage with this approach is that the foam tends to deteriorate under exposure to the outdoor environment. A more significant disadvantage is that foam windsocks tend to be effective only up to a certain minimal wind velocity. Therefore, the Knutson et al. solution is not effective under high air turbulence where there are relatively high winds or where the microphone is moving at a high rate of speed.
Another approach, U.S. Pat. No. 4,570,746 to Das et al. and assigned to International Business Machines, teaches use of a wind/breath screen enclosing a microphone and part of a microphone cable extending from the microphone. Das et al. disclose the wind/breath screen including a rigid perforated structure having two semi-spheres hinged together to form a full perforated sphere for mounting over the microphone. The sphere is supported by and snaps shut around a grommet that encircles the microphone cable. Additionally, a latex foam layer is mounted to and surrounds the sphere. Thus, Das et al. teach that a pad of dead air results between the sphere and the microphone. Unfortunately, however, Das et al. does not fully solve the problems with the Knutson et al. reference. The foam layer is still not effective under high air turbulence regardless of the dead layer of air and the heavily perforated sphere. Air turbulence impulses can still penetrate the foam, the perforated sphere, and the dead air, and can still impinge on the microphone.
Still another approach is disclosed in U.S. Pat. No. 5,288,955 to Staple et al. assigned to Motorola, Inc., which teaches a microphone mounting arrangement for reducing noise arising from wind and vibration. Staple et al. disclose the microphone mounting arrangement including a bullet-shaped tubular housing having a rounded front portion and a flat rear portion. The tubular housing is shown mounted to the handlebars of a bicycle. A microphone is mounted within the tubular housing in the flat rear portion thereof and is secured therein by a round rubber boot. A disadvantage, however, is that the Staple et al. microphone lacks the benefits of a foam windsock. Another disadvantage is that the Staple et al. microphone is specially and newly designed and is not adaptable to already existing and readily available microphones. Thus, the Staple et al. microphone is a cost prohibitive solution to the above-mentioned problems in the prior art.
Other approaches include various electronic signal processing techniques to either filter out unwanted noise and/or to cancel out such noise. Unfortunately, such high-tech, high-cost approaches involving noise filtering and canceling do not sufficiently attenuate environmental noises, especially wind noise. In fact, these electronic approaches usually reduce environmental noise but do so at the expense of attenuating desired sound signals, and degrading sound clarity and overall quality.
Motorcycle enthusiasts are particularly interested in microphone technology involving environmental noise attenuation. U.S. Pat. No. 4,979,586 to Lazzeroni et al. exemplifies a typical helmet headset that is very popular among motorcycle riders, and that is associated with the J&M Corporation of Tucson, Ariz. Such headsets include a foam-covered microphone that is positioned directly in front of a motorcyclist's mouth and that is supported by a flexible boom that attaches to one side of a helmet. Such headsets are used as communication systems in speech between a motorcycle driver and passenger, as well as between motorcycle drivers on different motorcycles. The headsets are also used to plug into and transmit signals from on-board AM/FM radio equipment.
Motorcycle helmet headsets are particularly susceptible to environmental noises including that from headwind, crosswind, nearby traffic, tunnel echoes, and motorcycle engine noise. Motorcyclists prefer that a headset microphone transmit only desired speech in a clear manner. Unfortunately, however, environmental noise is a significant problem for a couple of reasons. First, the environmental noise degrades microphone transmission quality as discussed previously. Additionally, the environmental noise tends to inadvertently interrupt radio signals being transmitted from the on-board AM/FM radio to the speakers of the headset. Motorcycle riders tend to find this annoying and inconvenient. Voice activated technology (VOX) may be responsible for this problem. VOX often misinterprets environmental noise as desired speech and cuts out the radio signal, subordinating it to the headset communication system.
Accordingly, U.S. Pat. No. 5,243,659 to Lazzeroni et al. teaches an improved VOX system that automatically compensates for increased environmental noise so that a motorcycle rider does not have to adjust the sensitivity settings of the VOX to avoid the above-described interruption problem. Unfortunately, such a solution amounts to yet another of the many electronic signal processing techniques, which are not fully adequate to solve the environmental noise problems of the prior art, as discussed above.
From the above, it can be appreciated that microphone devices of the prior art are not fully optimized to adequately suppress unwanted environmental noise. Therefore, what is needed is a simple and cost-effective solution that is readily adaptable for use with existing microphones and that significantly isolates desired microphone input signals from undesired environmental noise to improve microphone performance.